BS EN 62058-21:2010

BSI Standards Publication

Electricity metering
equipment (a.c.) —
Acceptance inspection
Part 21: Particular requirements for
electromechanical meters for active
energy (classes 0,5, 1 and 2 and class
indexes A and B)


BRITISH STANDARD

BS EN 62058-21:2010
National foreword

This British Standard is the UK implementation of EN 62058-21:2010. It was
derived by CENELEC from IEC 62058-21:2008. Together with BS EN 6205811:2010, it supersedes BS EN 60514:1995 which is withdrawn.
The CENELEC common modifications have been implemented at the appropriate places in the text and are indicated by tags (e.g. }~ ).
The UK participation in its preparation was entrusted to Technical Committee
PEL/13, Electricity Meters.
A list of organizations represented on this committee can be obtained on
request to its secretary.
This publication does not purport to include all the necessary provisions of a
contract. Users are responsible for its correct application.
© BSI 2010
ISBN 978 0 580 59107 5
ICS 17.220.20; 91.140.50

Compliance with a British Standard cannot confer immunity from
legal obligations.
This British Standard was published under the authority of the Standards
Policy and Strategy Committee on 30 September 2010.

Amendments/corrigenda issued since publication
Date

Text affected


EUROPEAN STANDARD

EN 62058-21

NORME EUROPÉENNE
EUROPÄISCHE NORM

June 2010

ICS 17.220; 91.140.50

Supersedes EN 60514:1995 (partially)

English version

Electricity metering equipment (a.c.) Acceptance inspection Part 21: Particular requirements for electromechanical meters for active
energy (classes 0,5, 1 and 2 and class indexes A and B)
(IEC 62058-21:2008, modified)
Equipement de comptage

de l'électricité (a.c.) Contrôle de réception Partie 21: Exigences particulières
pour compteurs électromécaniques
d'énergie active (classes 0,5, 1 et 2
et indices de classe A et B)
(CEI 62058-21:2008, modifiée)

Wechselstrom-Elektrizitätszähler Annahmeprüfung Teil 21: Besondere Anforderungen
an elektromechanische Zähler
für Wirkenergie (Klassen 0,5, 1 und 2
und Klassenzeichen A und B)
(IEC 62058-21:2008, modifiziert)

This European Standard was approved by CENELEC on 2010-06-01. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2010 CENELEC -

All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62058-21:2010 E


BS EN 62058-21:2010
EN 62058-21:2010

–2–

Foreword
The text of document 13/1431/FDIS, future edition 1 of IEC 62058-21, prepared by IEC TC 13, Electrical
energy measurement, tariff- and load control, was submitted to the IEC-CENELEC parallel vote.
A draft amendment, prepared by the Technical Committee CENELEC TC 13, Equipment for electrical
energy measurement and load control, was submitted to the formal vote.
The combined texts were approved by CENELEC as EN 62058-21 on 2010-06-01.
EN 62058-21:2010, together with EN 62058-11:2010, supersedes EN 60514:1995.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent
rights.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement

(dop)

2011-06-01


– latest date by which the national standards conflicting
with the EN have to be withdrawn

(dow)

2013-06-01

This European Standard has been prepared under a mandate given to CENELEC by the European
Commission and the European Free Trade Association and covers essential requirements of
EC Directive 2004/22/EC. See Annex ZZ.
Annexes ZA and ZZ have been added by CENELEC.
__________

Endorsement notice
The text of the International Standard IEC 62058-11:2008 was approved by CENELEC as a European
Standard with agreed common modifications.


BS EN 62058-21:2010
EN 62058-21:2010

–3–

Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.

NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.

Publication

Year

Title

EN/HD

Year

IEC 62058-11

2008

Electricity metering equipment (AC) Acceptance inspection Part 11: General acceptance inspection
methods

EN 62058-11

2010

ISO/IEC Guide 98

1995

Guide to the expression of uncertainty in
measurement (GUM)


-

-


BS EN 62058-21:2010
EN 62058-21:2010

–4–

Annex ZZ
(informative)
Coverage of Essential Requirements of the EC Directives
This European Standard has been prepared under the mandate M/374 given to CENELEC by the
European Commission and within its scope, the standard covers methods for statistical verification of
conformity with the metrological requirements in connection the Modules F, D and H1.
EN 62058-11 specifies sampling plans, schemes and systems for lot-by-lot inspection by attributes or
variables. In addition, a test procedure for 100 % inspection is specified, that can be used if the lot size is
too small for sampling inspection or when sampling inspection has to be discontinued.
Considering the Part 11, EN 62058-21 specifies particular requirements for electromechanical electricity
meters, including the tests to be performed, the sampling plans applicable and the performance criteria.
Table ZZ.1 provides the relationship between the Essential requirements of the MID and the stipulations
of the EN 62058 series.
Compliance with this standard provides one means of conformity with the specified essential
requirements of the Directives concerned.
WARNING: Other requirements and other EC Directives may be applicable to the products falling within
the scope of this standard.



BS EN 62058-21:2010
EN 62058-21:2010

–5–

Table ZZ.1 – Relationship between the Essential requirements of the MID
and the stipulations of the relevant standards
MID Annex I

Subject

EN 62058-11

EN 62058-21

EN 62058-31

–

5.6 Accuracy
tests, Table
Z2
5.7
Verification of
the register

5.6 Accuracy
tests, Table
Z2
5.7

Verification of
the register

NOTE The text in this column is
for orientation. For the full text see
the MID.
1

Allowable Errors
1.1

Under rated operating conditions
and in the absence of disturbance

1.2

Under rated operating conditions
and in the presence of disturbance

–

–

–

1.3

Climatic, mechanical and EM
environment and other influence
quantities to be specified by the

manufacturer

–

–

–

1.3.1

Climatic environments, upper and
lower temperature limit

–

–

–

1.3.2

Mechanical environments,
vibration and shock

–

–

–


1.3.3

Electromagnetic environments,
unless otherwise laid down in the
appropriate instrument-specific
annexes.

–

–

–

1.3.4

Other influence quantities

–

–

–

1.4

Carrying out the tests

–

–


–

1.4.1

Basic rules for testing and
determination of errors

–

5.6,
Accuracy test

5.6,
Accuracy test

1.4.2

Ambient humidity

–

–

–

2

Reproducibility


–

–

–

3

Repeatability

–

4.3

4.3

4

Discrimination and Sensitivity

–

–

–

5

Durability


–

–

–

6

Reliability

–

–

–

7

Suitability

5.3
AC voltage
test

5.3
AC voltage
test

7.1


7.2

No feature likely to facilitate
fraudulent use, possibilities for
unintentional misuse minimal

–

–

–

Suitable for intended use under
practical working conditions, no
unreasonable demand of the user

–

–

–


BS EN 62058-21:2010
EN 62058-21:2010

MID Annex I

7.3


7.4

7.5

7.6

8
8.1

8.2

8.3

–6–

Subject

EN 62058-11

EN 62058-21

EN 62058-31

–

–

–

N.A.


N.A.

N.A.

Robust and materials of
construction suitable for the
intended use conditions.

–

–

–

Designed so as to allow the control
of the measuring tasks after the
instrument has been placed on the
market and put into use.
Software that is critical for the
metrological characteristics
identifiable.
Metrological characteristics not
inadmissibly influenced by the
associated software.

–

–


–

Protection against corruption

–

–

–

Metrological characteristics not
influenced in any inadmissible way
by the connection to it of another
device, by any feature of the
connected device itself or by any
remote device that communicates
with the measuring instrument.

–

–

–

Hardware component critical for
metrological characteristics
designed so that it can be secured.
Security measures to provide
evidence of an intervention.


–

–

–

–

–

–

Measurement data, critical software and
metrologically important parameters
stored
or
transmitted
adequately
protected
against
accidental
or
intentional corruption.

–

–

–


For utility measuring instruments the
display of the total quantity supplied or
the displays from which the total quantity
supplied can be derived, whole or partial
reference to which is the basis for
payment, shall not be able to be reset
during use.

–

–

–

Errors of a utility measuring
instrument at flows or currents
outside the controlled range not
unduly biased.
When the measurand is constant
over time, the measuring
instrument shall be insensitive to
small fluctuations of the value of
the measurand, or shall take
appropriate action.

Software that is critical for metrological
characteristics shall be identified as such
and shall be secured.
Software identification.
Evidence of an intervention available for

a reasonable period of time.

8.4

8.5


BS EN 62058-21:2010
EN 62058-21:2010

–7–

MID Annex I

9
9.1

Subject

EN 62058-11

EN 62058-21

EN 62058-31

Information to be borne by and to
accompany the instrument

–


–

–

–

5.2

5.2

N.A.

N.A.

N.A.

–

–

–

Shall bear the following
inscriptions:
- manufacturers mark or name;
- information in respect of
accuracy.
When applicable:
-


-

9.2

9.3

information in respect of the
conditions of use;
measuring capacity;
measuring range;
identity marking;
number of the EC-type examination
certificate or the EC design
examination certificate;
information whether or not additional
devices providing metrological
results comply with the provisions of
this Directive on legal metrological
control.

For too small instruments, marking
on packaging and in any
accompanying documents
Accompanying information on
- operation
and where relevant
- rated operating conditions;
- mechanical and
electromagnetic environment
classes;

the upper and lower
temperature limit, whether
condensation is possible or
not, open or closed location;
- instructions for installation,
maintenance, repairs,
permissible adjustments;
- instructions for correct
operation and any special
conditions of use;
- conditions for compatibility with
interfaces, sub-assemblies or
measuring instruments.

9.4

Utility meters do not require
individual instruction manuals.

–

–

–

9.5

Decimal scale interval

–


–

–

9.6

Material measure

N.A.

N.A.

N.A.

9.7

Units of measurement and
symbols in accordance with
Community legislation

–

–

–

Marks and inscriptions clear, nonerasable, unambiguous and nontransferable.

–


–

–

9.8


BS EN 62058-21:2010
EN 62058-21:2010

MID Annex I

10

–8–

Subject

Indication of result

EN 62058-11

EN 62058-21

EN 62058-31

–

–


–

10.1

Display or hard copy

N.A.

N.A.

N.A.

10.2

Indication of result clear and
unambiguous. Easy reading.

N.A.

N.A.

N.A.

10.3

Hard copy easily legible and not
erasable

N.A.


N.A.

N.A.

10.4

Direct sales trading transactions

N.A.

N.A.

N.A.

10.5

Fitted with a metrologically controlled
display accessible without tools to the
consumer.

5.7
Verification of
the register

5.7
Verification of
the register

5.7

Verification of
the register

Further processing of data to
conclude the trading transaction

N.A.

N.A.

N.A.

Durable record of the
measurement result (other than
utility meter)

N.A.

N.A.

N.A.

Durable proof of the measurement
result

N.A.

N.A.

N.A.


–

–

–

The reading of this display is the
measurement result that serves as the
basis for the price to pay.

11
11.1

11.2
12

Conformity evaluation
Designed so as to allow ready
evaluation of its conformity with
the appropriate requirements of
this Directive.

Annex MI003

ACTIVE ELECTRICAL ENERGY
METERS

1


Accuracy

–

–

–

2

Rated operating conditions

–

–

–

3

MPEs

5.6 Accuracy
tests, Table
Z2
5.7
Verification of
the register

5.6 Accuracy

tests, Table
Z2
5.7
Verification of
the register

4

Permissible effect of disturbances

–

–

–

4.1

General – Special EM environment

–

–

–

4.2

Effect of disturbances of long
duration


–

–

–

Reversed phase sequence

–

–

–

Voltage unbalance (only applicable to
polyphase meters)

–

–

–

Harmonic contents in the current circuits

–

–


–

DC and harmonics in the current circuit

–

–

–

Fast transient bursts

–

–

–


BS EN 62058-21:2010
EN 62058-21:2010

–9–

MID Annex I

EN 62058-11

EN 62058-21


EN 62058-31

Magnetic fields

–

–

–

HF (radiated RF) electromagnetic field;

–

–

–

Conducted disturbances
introduced by radio-frequency
fields

–

–

–

Oscillatory waves immunity


–

–

–

4.3

Permissible effect of transient
electromagnetic phenomena

–

–

–

4.3.1

Behavior during and immediately
after a disturbance
Recovery
Critical change value

–

–

–


Critical change value for
overcurrent

–

–

–

4.3.2
5

Subject

Suitability
5.1

Measurement error below the rated
operating voltage

–

–

–

5.2

Display of total energy
- sufficient number of digits

- not resettable during use

–

–

–

5.3

Retain energy register reading for
4 months

–

–

–

5.4

Running with no load

5.5

Starting

–

5.4 Test of

no-load
condition

5.4 Test of
no-load
condition

–

5.5 Starting,
Table Z1

5.5 Starting,
Table Z1

6

Units

–

–

–

7

Putting into use

–


–

–

Specifies
100% testing
and sampling
inspection
methods to
support
modules F, D
and H1

–

–

CONFORMITY ASSESSMENT
B + F or B + D or H1.


BS EN 62058-21:2010
EN 62058-21:2010

– 10 –

CONTENTS
INTRODUCTION...................................................................................................................11
1


Scope .............................................................................................................................12

2

Normative references .....................................................................................................12

3

Terms, definitions, symbols and abbreviations................................................................12

4

Test conditions ...............................................................................................................12

5

4.1 Place of inspection ................................................................................................12
4.2 Reference conditions.............................................................................................12
4.3 Uncertainty of measurement of percentage error ...................................................14
4.4 Cover and seal ......................................................................................................15
Inspection procedure ......................................................................................................15

6

5.1 Tests to be performed and inspection methods......................................................15
5.2 Preliminary tests and pre-conditioning ................................................................... 16
5.3 Test No. 1: AC voltage test.................................................................................... 16
5.4 Test No. 2: Test of no-load condition ..................................................................... 17
5.5 Test No. 3: Starting ............................................................................................... 17

5.6 Tests No. 4 to 9: Accuracy tests ............................................................................ 17
5.7 Test No. 10: Verification of the register .................................................................20
5.8 Other tests ............................................................................................................20
Criteria for lot acceptance non-acceptance, disposal of unacceptable lots ......................20

7

Test record and evaluation .............................................................................................21

Bibliography..........................................................................................................................23
Table 1 – Voltage and current unbalance for polyphase meters ............................................12
Table 2 – Reference conditions.............................................................................................13
Table 3 – Percentage error limits corrected with uncertainty .................................................15
Table 4 – Acceptance tests and inspection methods ............................................................. 16
Table 5 – AC voltage test...................................................................................................... 17
Table 6 – Value of current for starting test ............................................................................ 17
Table 7 – Accuracy test points and limits of percentage error .............................................. 18
Table 8 – Inspection sheet ....................................................................................................22
Table Z1 – Value of current for starting test for meters of class index A and B ....................................17
Table Z2 – Accuracy test points and limits of errors for meters of class index A and B .......................18
Table Z3 – Example for determining the percentage error limits to be applied .....................................20


– 11 –

BS EN 62058-21:2010
EN 62058-21:2010

INTRODUCTION
This standard together with IEC 62058-11 cancels and replaces IEC 60514, Acceptance

inspection of class 2 alternating-current watt-hour meters, which was a Technical Report.


BS EN 62058-21:2010
EN 62058-21:2010

– 12 –

ELECTRICITY METERING EQUIPMENT (a.c.) –
ACCEPTANCE INSPECTION –
Part 21: Particular requirements for electromechanical meters
for active energy (classes 0,5, 1 and 2 }and class indexes A and B~)

1

Scope

This part of IEC 62058 specifies particular requirements for acceptance inspection of newly
manufactured direct connected or transformer operated electromechanical meters for active
energy (classes 0,5, 1 and 2) delivered in lots in quantities above 50. The method of
acceptance of smaller lots should be agreed upon by the manufacturer and the customer.
The process described herein is primarily intended for acceptance inspection between the
manufacturer and the purchaser.
}This European standard applies to meters of accuracy classes 0,5, 1 and 2, as well as to meters of class
indexes A and B. ~
NOTE

2

It can also be used for other purposes, for example to support initial verification.


Normative references

The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 62058-11:2008, Electricity metering equipment (a.c.) – Acceptance inspection – Part 11:
General acceptance inspection methods
ISO/IEC GUIDE 98: 1995, Guide to the Expression of Uncertainty in Measurement
} EN 50470-1:2006, Electricity metering equipment (a.c.) - Part 1: General requirements, tests and test conditions Metering equipment (class indexes A, B and C)

EN 50470-2:2006, Electricity metering equipment (a.c.) - Part 2: Particular requirements meters for active energy (class indexes A and B)~

3

Electromechanical

Terms, definitions, symbols and abbreviations

For the purposes of this document, the terms, definitions, symbols and abbreviations of
IEC 62058-11 apply.

4
4.1

Test conditions
Place of inspection

Subclause 5.15 of IEC 62058-11 applies.
4.2


Reference conditions

The tests shall be carried out under the following conditions:
Table 1 – Voltage and current unbalance for polyphase meters
Condition
Each of the voltages between phase and neutral and between any two
phases shall not differ from the average corresponding voltage by more
than

Class of meter
0,5

1

2

± 0,5 %

±1%

±1%


BS EN 62058-21:2010
EN 62058-21:2010

– 13 –

Class of meter


Condition
Each of the currents in the conductors shall not differ from the average
current by more than

0,5

1

2

±1%

±2%

±2%

The phase displacements of each of these currents from the
corresponding phase-to-neutral voltage, irrespective of the phase angle,
shall not differ from each other by more than

2°

Table 2 – Reference conditions

Influence quantity

Permissible tolerances
for meters of class


Reference value
0,5

1

2

± 1 °C

± 2 °C

± 2 °C

Ambient temperature

Reference temperature or, in its
absence, 23 °C a

Voltage

Reference voltage

± 0,5 %

± 1,0 %

± 1,0 %

Frequency


Reference frequency

± 0,2 %

± 0,3 %

± 0,5 %

Phase sequence

L1 – L2 – L3

-

Voltage unbalance

All phases connected

-

Wave-form

Sinusoidal voltages and currents

Continuous magnetic
induction of external origin

Equal to zero

Magnetic induction of

external origin at the
reference frequency

Distortion factor less than
2%

2%
-

Induction value which causes a
variation of error not greater than
Magnetic induction equal to zero

± 0,1 %

± 0,2 %

b

± 0,3 %

but should in any case be smaller than
0,05 mT

Operation of accessories

3%

No operation of accessories


Working position

Vertical working position

Conducted disturbances,
induced by radio frequency
fields, 150 kHz to 80 MHz

Equal to zero

c

b

± 0,5 °
<1V

a

If the tests are made at a temperature other than the reference temperature, including permissible tolerances, the
results shall be corrected by applying the appropriate temperature coefficient of the meter.

b

The test consists of
1) for a single-phase meter, determining the errors first with the meter normally connected to the mains and then
after inverting the connections to the current circuits as well as to the voltage circuits. Half of the difference
between the two errors is the value of the variation of error. Because of the unknown phase of the external
field, the test should be made at 0,1 I b resp. 0,05 I n at unity power factor and 0,2 I b resp. 0,1 I n at 0,5 power
factor;

2) for a three-phase meter, making three measurements at 0,1 I b resp. 0,05 I n at unity power factor, after each of
which the connection to the current circuits and to the voltage circuits are changed over 120° while the phase
sequence is not altered. The greatest difference between each of the errors so determined and their average
value is the value of the variation of error.

c

Determination of the vertical working position (see IEC 62053-11, 5.1).
The construction and assembly of the meter should be such that the correct vertical position is ensured (in both
the front-to-back and left-to-right vertical planes) when
–

the base of the meter is supported against a vertical wall, and

–

a reference edge (such as the lower edge of the terminal block) or a reference line marked on the meter case
is horizontal.


BS EN 62058-21:2010
EN 62058-21:2010

– 14 –

} For meters of class index A and B, the values in Table 1 and Table 2, specified for meters of class 2 and
class 1 apply respectively.~
4.3

Uncertainty of measurement of percentage error


The measuring process shall be such that the uncertainty of the measurement of the
th
percentage error should not exceed 1/5 of the limit of percentage error for the given test
point at reference conditions.
For determining the uncertainty of measurement, see ISO/IEC GUIDE 98.
If the uncertainty exceeds this limit, then inspection by variables cannot be used. Only
inspection by attributes will be possible, and the limits of percentage error shall be corrected
using the following formula:

ecorr ( I , cos ϕ) = 6 / 5 • e( I , cos ϕ) − U
where:
•

e( I , cos ϕ) is the limit of percentage error for the given test point at reference conditions;

•

U is the measurement uncertainty.

EXAMPLE

If, for a given test point, the limit of percentage error at reference conditions is

e( I , cos ϕ) = ± 2 % ; and
U = 0,5 %; then

ecorr ( I , cos ϕ) = ± (6 / 5 • 2,0 − 0,5) = ±1,9% .
Instead of the original limit, this corrected limit applies.
Table 3 gives percentage error limits corrected with uncertainty of measurement, using the

formula above.


BS EN 62058-21:2010
EN 62058-21:2010

– 15 –

Table 3 – Percentage error limits corrected with uncertainty
Percentage
error
limit %

Uncertainty of measurement of percentage error, %
0,6

0,5

0,45

0,4

0,35

0,3

0,25

0,2


0,15

0,1

± 3,0

± 3,0

± 3,0

± 3,0

± 3,0

± 3,0

± 3,0

± 3,0

± 3,0

± 3,0

± 3,0

± 2,5

± 2,4


± 2,5

± 2,5

± 2,5

± 2,5

± 2,5

± 2,5

± 2,5

± 2,5

± 2,5

± 2,0

± 1,8

± 1,9

± 1,95

± 2,0

± 2,0


± 2,0

± 2,0

± 2,0

± 2,0

± 2,0

± 1,5

± 1,2

± 1,3

± 1,35

± 1,4

± 1,45

± 1,5

± 1,5

± 1,5

± 1,5


± 1,5

± 1,0

± 0,6

± 0,7

± 0,75

± 0,8

± 0,85

± 0,9

± 0,95

± 1,0

± 1,0

± 1,0

± 0,6

± 0,12

± 0,22


± 0,27

± 0,32

± 0,37

± 0,42

± 0,47

± 0,52

± 0,57

± 0,6

± 0,5

0

± 0,1

± 0,15

± 0,2

± 0,25

± 0,3


± 0,35

± 0,4

± 0,45

± 0,5

± 0,4

0

0

± 0,03

± 0,08

± 0,13

± 0,18

± 0,23

± 0,28

± 0,33

± 0,38


± 0,3

0

0

0

0

± 0,01

± 0,06

± 0,11

± 0,16

± 0,21

± 0,26

± 0,2

0

0

0


0

0

0

0

± 0,04

± 0,09

± 0,14

NOTE

In any case, the uncertainty should not exceed half of the percentage error limit.

4.4

Cover and seal

The meters shall be inspected and tested with their covers on and manufacturer's seal
unbroken.
NOTE If testing of mechanical aspects is required, the conditions should be agreed between the manufacturers
and the purchaser.

5
5.1


Inspection procedure
Tests to be performed and inspection methods

Table 4 specifies the characteristics to be inspected, the classification of nonconformities, and
the inspection method(s) that can be applied, with reference to the sampling plans given in
IEC 62058-11.


BS EN 62058-21:2010
EN 62058-21:2010

– 16 –

Table 4 – Acceptance tests and inspection methods
Test No.

1

2

3

Test

Classification of
nonconformities

AC voltage
test


No-load

Starting

Critical

Non-critical

Inspection methods available

a

IEC 62058-11
sampling plan

Lot-by-lot inspection by attributes,
single sampling, Ac = 0
or

Table 6

Isolated lot inspection by attributes,
procedure A, Ac = 0

Table 18

Lot-by-lot inspection by attributes,
single sampling, AQL = 1,0
or


Table 2

Lot-by-lot inspection by attributes,
double sampling, AQL = 1,0
or

Table 7

Isolated lot inspection by attributes,
single or double sampling,
Procedure A, LQ = 5,0
or

Table 17

Isolated lot inspection by attributes,
single or double sampling,
Procedure B, LQ = 5,0

Table 20

Non-critical

As for test No.2
As for test No. 2, in addition

4…9

a


Accuracy

10

Meter
constant

-

Other tests

Non-critical

Lot-by-lot inspection by variables,
“s” method, AQL = 1,0
or

Table 24

Lot-by-lot inspection by variables,
“ σ ” method, AQL = 1,0

Table 26

Critical

As for test No. 1
See 5.8

-


100 % inspection can always be used, see Clause 6 of IEC 62058-11.

If, for the different tests, the sampling plans give different sample sizes, then the number of
samples shall be equal to the largest sample size. The smaller sample shall be chosen from
the larger sample randomly.
}See also EN 62058-11, 5.5.~
5.2

Preliminary tests and pre-conditioning

The meters selected for inspection shall be visually examined in order to verify that they
belong to the same type, that their specified markings are correct and that none of them
shows signs of damage. The meters shall be in conformity with the type approval and they
shall have the same voltage and current charactesristics.
Before the tests, the meters shall be energized at reference voltage and loaded with the
current specified below, at unity power factor, to reach thermal stability.
The value of the current shall be 0,1 I b for direct connected meters or 0,1 I n for transformer
operated meters respectively.
The tests shall be performed in the order below.
}For meters of class indexes A and B, the value of the current shall be Itr.~
5.3

Test No. 1: AC voltage test

The a.c. voltage test shall be carried out in accordance with Table 5.


BS EN 62058-21:2010
EN 62058-21:2010


– 17 –

The test voltage shall be substantially sinusoidal, having a frequency between 45 Hz and
65 Hz, and applied for 2 s. The power source shall be capable of supplying at least 500 VA.
The rise time and the fall time of the test voltage shall be ≤ 2 s. The auxiliary circuits with
reference voltage equal to or below 40 V shall be connected to earth.
During this test, no flashover, disruptive discharge or puncture shall occur.
Table 5 – AC voltage test
Test voltage r.m.s for meters of
insulation class
I

II

1,6 kV

3,2 kV

Points of application of the test voltage
Between on the one hand, all the current and voltage circuits as well as the
auxiliary circuits whose reference voltage is over 40 V, connected together,
and, on the other hand, earth.

If the manufacturer provides evidence that the test has been already performed on each item
before acceptance inspection, then this test does not have to be performed.
5.4

Test No. 2: Test of no-load condition


When the meter is energized at reference voltage, at unity power factor and with the test
current applied, and connected as shown in the diagram of connections, the rotor shall not
make a complete revolution.
For drum-type registers, these conditions shall apply with only one drum moving.
The value of the test current shall be 0,001 I b , in case of direct connected meters or 0,001 I n
in case of transformer operated meters.
NOTE

Unlike during type testing, the test is done with a small current, because the test conditions are different.

}The value of the test current for meters of class indexes A and B shall be 0,01 Itr.~
5.5

Test No. 3: Starting

When the meter is energized at reference voltage, (and in case of polyphase meters, with
balanced load) and connected as shown in the diagram of connections, the rotor shall start
and make more than one revolution at the current given in Table 6.
For meters with drum-type registers, the test shall be made with not more than two drums
moving.
Table 6 – Value of current for starting test
Meters for
Direct connection
Connection through current transformers

Class of meter

Power factor

0,5


1

2

--

0,004 I b

0,005 I b

1

0,002 I n

0,002 I n

0,003 I n

1

} For meters of class index A and B, instead of the values of Table 6, the values of Table Z1 apply:
Table Z1 – Value of current for starting test for meters of class index A and B
Meters for

5.6

Meters of class index

Power factor


A

B

Direct connection

0,05 Itr

0,04 Itr

1

Connection through current
transformers

0,06 Itr

0,04 Itr

1
~

Tests No. 4 to 9: Accuracy tests

The accuracy tests for single phase or polyphase meters shall be carried out at the test points
specified in Table 7, in the order shown in the table, without waiting for thermal equilibrium to
be attained between the measurements.



BS EN 62058-21:2010
EN 62058-21:2010

– 18 –

Table 7 – Accuracy test points and limits of percentage error
Value of current for
Test
No.

Power
factor

Limits of percentage
error
for meters of class

Applicable
for meter
type

Load
(in case of
polyphase
meters)

0,5 S

1


2

Direct
connected
meters

Transformer
operated
meters

4

0,05 I b

0,02 I n

1

Single- and
polyphase

Balanced

± 1,0

± 1,5

± 2,5

5


Ib

In

1

Single- and
polyphase

Balanced

± 0,5

± 1,0

± 2,0

6

Ib

In

0,5

Single- and
polyphase

Balanced


± 0,8

± 1,0

± 2,0

7

Ib

In

1

Polyphase

Single
phase a

± 1,5

± 2,0

± 3,0

8

Ib


In

1

Polyphase

Single
phase b

± 1,5

± 2,0

± 3,0

9

I max

I max

1

Single- and
polyphase

Balanced

± 0,5


± 1,0

± 2,0

a

The meter shall be supplied with three phase symmetrical voltage. The current shall be applied to
any of the phases.

b

The meter shall be supplied with three phase symmetrical voltage. The current shall be applied to a
phase different from the phase in test 7.

} For meters of class index A and B, instead of the values of the values of Table 7, the values of Table Z2
apply:
Table Z2 – Accuracy test points and limits of errors for meters of class index A and B
Value of current for direct
connected and
transformer operated
meters

Power
factor

Applicable
for meter
type

Load

(in case of
polyphase
meters)

4

Imin

1

Singleand
polyphase

5

10 Itr

1

6

10 Itr

7

Test No.

a

b


Percentage error limits for
for meters of class index
A

B

Balanced

± 2,5

± 1,5

Singleand
polyphase

Balanced

± 2,0

± 1,0

0,5

Singleand
polyphase

Balanced

± 2,0


± 1,0

10 Itr

1

Polyphase

Single
a
phase

± 3,0

± 2,0

8

10 Itr

1

Polyphase

Single
b
phase

± 3,0


± 2,0

9

Imax

1

Singleand
polyphase

Balanced

± 2,0

± 1,0

The meter shall be supplied with three phase symmetrical voltage. The current shall be
applied to any of the phases.
The meter shall be supplied with three phase symmetrical voltage. The current shall be
applied to a phase different from the phase in test 7.
~


– 19 –

BS EN 62058-21:2010
EN 62058-21:2010


} The values of Table Z2 are taken from EN 50470-2, Table 4 and Table 5, Percentage error limits at
reference conditions.
To ensure that the requirements of EN 50470-2, Table 8, Maximum Permissible Error (MPE), are also
met, and with this the essential requirements of the MID are met, the actual percentage error limits to be
used during conformity assessment shall be established using the method described below.
For each test point, the values of variation of percentage error due to temperature, voltage and frequency
variation, established during type testing, shall be subtracted from the MPE using the formula:
2
2
2
ecalc ( I , cos ϕ ) = MPE 2 − δ Type
(T , I , cos ϕ ) − δ Type
( U , I , cosϕ ) − δ Type
( f , I , cosϕ )

where:

ecalc ( I , cosϕ )

is the value of calculated limit of percentage error under reference conditions;

MPE

is the value of maximum permissible error taken from EN 50470-2, Table 8, for the
given test point;

δ Type (T , I , cos ϕ ) is the value of the variation of percentage error due to variation of temperature,
established during type testing;

δ Type ( U , I , cos ϕ )


is the value of the variation of percentage error due to variation of voltage,
established during type testing;

δ Type ( f , I , cos ϕ )

is the value of the variation of percentage error due to variation of frequency,
established during type testing.

The actual limit of percentage error to be applied for each test point shall be the lesser of the value shown
in Table Z1, and the value ecalc ( I , cos ϕ ) calculated as described above.
An eventual correction of the percentage error limits, due to uncertainty of the measurement of
percentage error as described in 4.3, also applies.
During manufacturing, the values of the variation of percentage error due to temperature, voltage and
frequency variation shall be established in adequate intervals to ensure that they are essentially same as
established during type testing.
EXAMPLE:
A meter of class index A, manufactured for the temperature range of 5 °C to 30 °C is tested.
The columns of Table Z3 show the following:
- column 1: the number of test, as identified in Table Z1;
-

column 2: the values of the mpe, taken from EN 50470-2, Table 8;

-

column 3: the values of temperature variation, established during the type test;

-


column 4: the values of voltage variation, established during the type test;

-

column 5: the values of frequency variation, established during the type test;

-

column 6: the calculated values of percentage error limits;

-

column 7: the percentage error limits taken from Table Z2. ~


BS EN 62058-21:2010
EN 62058-21:2010

– 20 –

} Table Z3 – Example for determining the percentage error limits to be applied
Tes
t
No.

4
5
6
7
8

9

MP
E

δ Type (T , I , cosϕ ) δ Type ( U , I , cos ϕ ) δ Type ( f , I , cos ϕ ) ecalc ( I , cos ϕ ) e( I , cos ϕ )

±
3,5

+ 0,5

- 0,2

+ 0,1

± 3,46

±
3,5

+ 0,3

- 0,2

+ 0,1

± 3,48

±

3,5

+ 0,5

- 0,2

+ 0,1

± 3,46

±
4,0

+ 0,4

- 0,2

+ 0,1

± 3,97

±
4,0

+ 0,4

- 0,2

+ 0,1


± 3,97

±
3,5

+ 0,3

- 0,2

+ 0,1

± 3,48

As the values of

± 2,5
± 2,0
± 2,0
± 3,0
± 3,0
± 2,0

e( I , cosϕ ) , taken from Table Z2 are smaller than the values ecalc ( I , cosϕ ) calculated

from the MPE taking into account the values of variation of percentage error due to temperature, voltage
and frequency variation, established during type testing, the values e( I , cosϕ ) of Table Z2 shall be
used.
If the meter is intended for a wider temperature range, then the calculation has to be performed for each
temperature range, and the smallest percentage error limits – out of all the calculated values
ecalc ( I , cosϕ ) and the values e( I , cosϕ ) of Table Z2 – shall be used. ~

5.7

Test No. 10: Verification of the register

This test shall be performed by measuring a sufficient amount of energy, to verify that the
accuracy of incrementing the register reading is better than ± 1,0 %.
The test shall be done for each meter on at least one tariff register.
5.8

Other tests

The manufacturer and the customer may agree to perform testing of any additional
functionality and mechanical aspects.
The inspection methods – 100 % testing, inspection by attributes or inspection by variables –
and the acceptance conditions shall be agreed by the manufacturer and the customer.
Some examples for mechanical testing are given below:
•

meshing of the register;

•

soldered and welded seams;

•

tightness of screws;

•


swarf, filings and metal dust especially in the air-gap(s) of the brake magnet(s);

•

any other item which is deemed desirable.

6

Criteria for lot acceptance non-acceptance, disposal of unacceptable lots

See IEC 62058-11, 5.18 and the relevant clauses for each inspection scheme.


– 21 –

7

BS EN 62058-21:2010
EN 62058-21:2010

Test record and evaluation

The test results of the sample shall be recorded and evaluated in the inspection sheet given
in Table 8 below.
NOTE

Tests agreed between the manufacturer and the purchaser may be added.

For larger sample sizes, several inspection sheets may be necessary. The results shall be
evaluated on the last sheet. In this case, in the line “Result” write “Continued on next

inspection sheet”. The cell “Lot number” can be used for numbering the inspection sheets
including test results of a lot.
For double sampling plans, two sets of inspection sheets may be necessary.


BS EN 62058-21:2010
EN 62058-21:2010

– 22 –

Table 8 – Inspection sheet
1 st / 2

nd

Meter

sample

Inspection by attributes

Inspection by attributes or variables
Test number

Last
figures of
serial no.

1


10

2

3

4

5

6

7

8

1
2
3
4
5
6
7
8
9
10
11
12
13
14

…
Number of
nonconformities
Number of
nonconforming
meters a
Acceptance number

0

0

Rejection number

1

1

Inspector

Measurement uncertainty
Percentage error limits ±
Sample mean

Date

xi

Standard deviation


si

f s or f σ
Lot number

MSSD or MPSD
pˆ
pˆ

pˆ

Ui

Li

i
n

∑ pˆ i =
i =1

Result: Accept /
Reject / 2 nd sample
a

See IEC 62058-11, 7.4.4.1.

p* =

9



– 23 –

BS EN 62058-21:2010
EN 62058-21:2010

Bibliography
IEC 62052-11:2003, Electricity metering equipment (a.c.) – General requirements, tests and
test conditions – Part 11: Metering equipment
NOTE Harmonized as EN 62052-11:2003 (not modified).

IEC 62053-11:2003, Electricity metering equipment (a.c.) – Particular requirements – Part 11:
Electromechanical meters for active energy (classes 0,5, 1 and 2)
NOTE Harmonized as EN 62053-11:2003 (not modified).

____________